scholarly journals A novel biparatopic antibody-ACE2 fusion that blocks SARS-CoV-2 infection: implications for therapy

2020 ◽  
Author(s):  
Xiaoniu Miao ◽  
Yi Luo ◽  
Xi Huang ◽  
Suki M. Y. Lee ◽  
Zhijun Yuan ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Virus Infection ◽  
Receptor Binding ◽  
Immune Therapy ◽  
Effective Vaccine ◽  
Receptor Binding Domain ◽  
New Class ◽  
Standard Assay ◽  
Positive Results

AbstractIn the absence of a proven effective vaccine preventing infection by SARS-CoV-2, or a proven drug to treat COVID-19, the positive results of passive immune therapy using convalescent serum provides a strong lead. We have developed a new class of tetravalent, biparatopic therapy, 89C8-ACE2. It combines the specificity of a monoclonal antibody (89C8) that recognizes the relatively conserved N-terminal domain (NTD) of the viral S glycoprotein, and the ectodomain of ACE2, which binds to the receptor-binding domain (RBD) of S. This molecule shows exceptional performance in vitro, inhibiting the interaction of recombinant S1 to ACE2 and transduction of ACE2-overexpressing cells by S-pseudotyped lentivirus with IC50s substantially below 100 pM, and with potency approximately 100-fold greater than ACE2-Fc itself. Moreover, 89C8-ACE2 was able to neutralize authentic virus infection in a standard assay at low nanomolar concentrations, making this class of molecule a promising lead for therapeutic applications.

scholarly journals Rapid production of SARS-CoV-2 receptor binding domain (RBD) and spike specific monoclonal antibody CR3022 in Nicotiana benthamiana

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kaewta Rattanapisit ◽  
Balamurugan Shanmugaraj ◽  
Suwimon Manopwisedjaroen ◽  
Priyo Budi Purwono ◽  
Konlavat Siriwattananon ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Receptor Binding ◽  
Nicotiana Benthamiana ◽  
Specific Binding ◽  
Expression System ◽  
Disease Diagnosis ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Global Public Health

Abstract Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the ongoing global outbreak of coronavirus disease (COVID-19) which is a significant threat to global public health. The rapid spread of COVID-19 necessitates the development of cost-effective technology platforms for the production of vaccines, drugs, and protein reagents for appropriate disease diagnosis and treatment. In this study, we explored the possibility of producing the receptor binding domain (RBD) of SARS-CoV-2 and an anti-SARS-CoV monoclonal antibody (mAb) CR3022 in Nicotiana benthamiana. Both RBD and mAb CR3022 were transiently produced with the highest expression level of 8 μg/g and 130 μg/g leaf fresh weight respectively at 3 days post-infiltration. The plant-produced RBD exhibited specific binding to the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2). Furthermore, the plant-produced mAb CR3022 binds to SARS-CoV-2, but fails to neutralize the virus in vitro. This is the first report showing the production of anti-SARS-CoV-2 RBD and mAb CR3022 in plants. Overall these findings provide a proof-of-concept for using plants as an expression system for the production of SARS-CoV-2 antigens and antibodies or similar other diagnostic reagents against SARS-CoV-2 rapidly, especially during epidemic or pandemic situation.

scholarly journals Isolation and comparative analysis of antibodies that broadly neutralize sarbecoviruses

2021 ◽  
Author(s):  
Lihong Liu ◽  
Sho Iketani ◽  
Yicheng Guo ◽  
Ryan Casner ◽  
Eswar Reddem ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Comparative Analysis ◽  
Receptor Binding ◽  
Comparative Studies ◽  
Human Monoclonal Antibody ◽  
Receptor Binding Domain ◽  
Pandemic Preparedness ◽  
Antibody Class

The devastation caused by SARS-CoV-2 has made clear the importance of pandemic preparedness. To address future zoonotic outbreaks due to related viruses in the sarbecovirus subgenus, we identified a human monoclonal antibody, 10-40, that neutralized or bound all sarbecoviruses tested in vitro and protected against SARS-CoV-2 and SARS-CoV in vivo. Comparative studies with other receptor-binding domain (RBD)-directed antibodies showed 10-40 to have the greatest breadth against sarbecoviruses and thus its promise as an agent for pandemic preparedness. Moreover, structural analyses on 10-40 and similar antibodies not only defined an epitope cluster in the inner face of the RBD that is well conserved among sarbecoviruses, but also uncovered a new antibody class with a common CDRH3 motif. Our analyses also suggested that elicitation of this class of antibodies may not be overly difficult, an observation that bodes well for the development of a pan-sarbecovirus vaccine.

scholarly journals SARS-CoV-2 receptor binding domain fusion protein efficiently neutralizes virus infection

2021 ◽  
Author(s):  
Abigael Chaouat ◽  
Hagit Achdout ◽  
Inbal Kol ◽  
Orit Berhani ◽  
Gil Roi ◽  
...  
Keyword(s):  
Virus Infection ◽  
Enzymatic Activity ◽  
Receptor Binding ◽  
Fusion Proteins ◽  
Surface Expression ◽  
Binding Domain ◽  
Host Cells ◽  
Virus Concentration ◽  
Receptor Binding Domain

AbstractSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the COVID-19 pandemic, causing health and economic problems. Currently, as dangerous mutations emerge there is an increased demand for specific treatments for SARS-CoV-2 infected patients. The spike glycoprotein on the virus membrane binds to the angiotensin converting enzyme 2 (ACE2) receptor on host cells through its receptor binding domain (RBD) to mediate virus entry. Thus, blocking this interaction may inhibit viral entry and consequently stop infection. Here, we generated fusion proteins composed of the extracellular portions of ACE2 and RBD fused to the Fc portion of human IgG1 (ACE2-Ig and RBD-Ig, respectively). We demonstrate that ACE2-Ig is enzymatically active and that it can be recognized by the SARS-CoV-2 RBD, independently of its enzymatic activity. We further show that RBD-Ig efficiently inhibits in vitro and in vivo SARS-CoV-2 infection, better than ACE2-Ig. Mechanistically we show that anti-spike antibodies generation, ACE2 enzymatic activity and ACE2 surface expression were not affected by RBD-Ig. Finally, we show that RBD-Ig is more efficient than ACE2-Ig at neutralizing high virus concentration infection. We thus propose that RBD-Ig physically blocks virus infection by binding to ACE2 and that RBD-Ig should be used for the treatment of SARS-CoV-2-infected patients.Author SummarySARS-CoV-2 infection caused serious socio-economic and health problems around the globe. As dangerous mutations emerge, there is an increased demand for specific treatments for SARS-CoV-2 infected patients. SARS-CoV-2 infection starts via binding of SARS-CoV-2 spike protein receptor binding domain (RBD) to its receptor, ACE2, on host cells. To intercept this binding, we generated Ig-fusion proteins. ACE2-Ig was generated to possibly block RBD by binding to it and RBD-Ig to block ACE2. We indeed showed that the fusion proteins bind to their respective target. We found that it is more efficient to inhibit SARS-CoV-2 infection by blocking ACE2 receptor with RBD-Ig. We also showed that RBD-Ig does not interfere with ACE2 activity or surface expression. Importantly, as our treatment does not target the virus directly, it may be efficient against any emerging variant. We propose here that RBD-Ig physically blocks virus infection by binding to ACE2 and thus it may be used for the treatment of SARS-CoV-2-infected patients.

scholarly journals A human monoclonal antibody targeting a conserved pocket in the SARS-CoV-2 receptor-binding domain core

2020 ◽  
Author(s):  
Juliette Fedry ◽  
Daniel L. Hurdiss ◽  
Chunyan Wang ◽  
Wentao Li ◽  
Gonzalo Obal ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Receptor Binding ◽  
Human Monoclonal Antibody ◽  
Binding Domain ◽  
Structural Basis ◽  
Binding Motif ◽  
Receptor Binding Domain ◽  
Hamster Model ◽  
Health Crisis

AbstractSARS-CoV-2 has caused a global outbreak of severe respiratory disease (COVID-19), leading to an unprecedented public health crisis. To date, there has been over thirty-three million diagnosed infections, and over one million deaths. No vaccine or targeted therapeutics are currently available. We previously identified a human monoclonal antibody, 47D11, capable of cross-neutralising SARS-CoV-2 and the related 2002/2003 SARS-CoV in vitro, and preventing SARS-CoV-2 induced pneumonia in a hamster model. Here we present the structural basis of its neutralization mechanism. We describe cryo-EM structures of trimeric SARS-CoV and SARS-CoV-2 spike ectodomains in complex with the 47D11 Fab. These data reveal that 47D11 binds specifically to the closed conformation of the receptor binding domain, distal to the ACE2 binding site. The CDRL3 stabilises the N343 glycan in an upright conformation, exposing a conserved and mutationally constrained hydrophobic pocket, into which the CDRH3 loop inserts two aromatic residues. Interestingly, 47D11 preferentially selects for the partially open conformation of the SARS-CoV-2 spike, suggesting that it could be used effectively in combination with other antibodies that target the exposed receptor-binding motif. Taken together, these results expose a cryptic site of vulnerability on the SARS-CoV-2 RBD and provide a structural roadmap for the development of 47D11 as a prophylactic or post-exposure therapy for COVID-19.

scholarly journals Stereotypic neutralizing VH antibodies against SARS-CoV-2 spike protein receptor binding domain in COVID-19 patients and healthy individuals

2021 ◽  
pp. eabd6990
Author(s):  
Sang Il Kim ◽  
Jinsung Noh ◽  
Sujeong Kim ◽  
Younggeun Choi ◽  
Duck Kyun Yoo ◽  
...  
Keyword(s):  
B Cells ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
De Novo ◽  
Binding Domain ◽  
Host Cells ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Healthy Individuals

Stereotypic antibody clonotypes exist in healthy individuals and may provide protective immunity against viral infections by neutralization. We observed that 13 out of 17 patients with COVID-19 had stereotypic variable heavy chain (VH) antibody clonotypes directed against the receptor-binding domain (RBD) of SARS-CoV-2 spike protein. These antibody clonotypes were comprised of immunoglobulin heavy variable (IGHV)3-53 or IGHV3-66 and immunoglobulin heavy joining (IGHJ)6 genes. These clonotypes included IgM, IgG3, IgG1, IgA1, IgG2, and IgA2 subtypes and had minimal somatic mutations, which suggested swift class switching after SARS-CoV-2 infection. The different immunoglobulin heavy variable chains were paired with diverse light chains resulting in binding to the RBD of SARS-CoV-2 spike protein. Human antibodies specific for the RBD can neutralize SARS-CoV-2 by inhibiting entry into host cells. We observed that one of these stereotypic neutralizing antibodies could inhibit viral replication in vitro using a clinical isolate of SARS-CoV-2. We also found that these VH clonotypes existed in six out of 10 healthy individuals, with IgM isotypes predominating. These findings suggest that stereotypic clonotypes can develop de novo from naïve B cells and not from memory B cells established from prior exposure to similar viruses. The expeditious and stereotypic expansion of these clonotypes may have occurred in patients infected with SARS-CoV-2 because they were already present.

scholarly journals Unreliable Measurement of Basophil Maximum Leukotriene Release with the Bühlmann CAST 2000 Enzyme-Linked Immunosorbent Assay Kit

2006 ◽  
Vol 13 (3) ◽  
pp. 420-422 ◽  
Author(s):  
S. E. Burastero ◽  
C. Paolucci ◽  
D. Breda ◽  
G. Monasterolo ◽  
R. E. Rossi ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Immunosorbent Assay ◽  
False Positive ◽  
Positive Control ◽  
Enzyme Linked Immunosorbent Assay ◽  
Positive Results

ABSTRACT The Bühlmann CAST 2000 enzyme-linked immunosorbent assay is a potentially useful assay for measuring sulfidoleukotrienes released in vitro by allergen-challenged basophils. However, we observed that the positive-control reagent yielded positive signals in cell-free systems. These false-positive results depended on using a mouse anti-FcεRI monoclonal antibody and were prevented by degranulation-inducing reagents other than mouse monoclonal antibodies.

scholarly journals Functional analysis of the receptor binding domain of SARS coronavirus S1 region and its monoclonal antibody

2014 ◽  
Vol 36 (3) ◽  
pp. 387-397 ◽  
Author(s):  
Hyun Kim ◽  
Yeongjin Hong ◽  
Keigo Shibayama ◽  
Yasuhiko Suzuki ◽  
Nobutaka Wakamiya ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Functional Analysis ◽  
Receptor Binding ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Sars Coronavirus

Discovery of potential inhibitors of the receptor-binding domain (RBD) of pandemic disease-causing SARS-CoV-2 Spike Glycoprotein from Triphala through molecular docking

2021 ◽  
Vol 01 ◽  
Author(s):  
Sharuk L. Khan ◽  
Falak A. Siddiqui ◽  
Mohd Sayeed Shaikh ◽  
Nitin V. Nema ◽  
Aijaz A. Shaikh
Keyword(s):  
Molecular Docking ◽  
Hydrogen Bonds ◽  
Receptor Binding ◽  
Chemical Constituents ◽  
Antioxidant Properties ◽  
Binding Domain ◽  
Quality Data ◽  
Receptor Binding Domain ◽  
Spike Glycoprotein

Background: COVID-19 (SARS-CoV-2 infection) has affected almost every region of the world. Presently, there is no defined line of treatment available for it. Triphala is already proven to have a safe biological window and well known for its antioxidant and immunomodulatory properties. Objective: Present work has been carried out to study Triphala's effectiveness for the treatment of COVID-19. Methods: The Receptor-binding domain (RBD) of SARS-CoV-2 Spike Glycoprotein responsible for the invasion into the host cell, which leads to further infection. The molecular docking (MD) was performed to explore the binding affinities (kcal/mol) of Triphala's chemical constituents and compared them with the existing drugs under investigation for the treatment of COVID-19 epidemiology. Results: Chebulinic acid binding affinity -8.5 kcal/mol with the formation of 10 hydrogen bonds. Almost all the major chemical constituents have formed two or more hydrogen bonds with RBD of SARS-CoV-2 Spike Glycoprotein. Conclusion: The present study showed that Triphala might perform vital roles in the treatment of COVID-19 and expand its usefulness to physicians to treat this illness. There is a need to complete the in-vitro, in-vivo biological testing of Triphala on SARS-CoV-2 disease to create more quality data. The binding mode of Chebulinic acid in the allosteric cavity allows a better understanding of RBD of SARS-CoV-2 Spike Glycoprotein target and provides insight for the design of new inhibitors. Triphala is already proven to have a safe biological window, which indicates we can skip the pre-clinical trials. Apart from this, Triphala is well known for its antioxidant properties, which ultimately improves the immunity of the COVID-19 patient.

scholarly journals A Potent SARS-CoV-2 Neutralizing Human Monoclonal Antibody That Reduces Viral Burden and Disease Severity in Syrian Hamsters

2020 ◽  
Vol 11 ◽  
Author(s):  
Anna C. Fagre ◽  
John Manhard ◽  
Rachel Adams ◽  
Miles Eckley ◽  
Shijun Zhan ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Disease Severity ◽  
Disease Burden ◽  
Human Monoclonal Antibody ◽  
Receptor Binding Domain ◽  
Yeast Display ◽  
Syrian Hamsters ◽  
Limited Efficacy ◽  
Protein Receptor

The emergence of COVID-19 has led to a pandemic that has caused millions of cases of disease, variable morbidity and hundreds of thousands of deaths. Currently, only remdesivir and dexamethasone have demonstrated limited efficacy, only slightly reducing disease burden, thus novel approaches for clinical management of COVID-19 are needed. We identified a panel of human monoclonal antibody clones from a yeast display library with specificity to the SARS-CoV-2 spike protein receptor binding domain that neutralized the virus in vitro. Administration of the lead antibody clone to Syrian hamsters challenged with SARS-CoV-2 significantly reduced viral load and histopathology score in the lungs. Moreover, the antibody interrupted monocyte infiltration into the lungs, which may have contributed to the reduction of disease severity by limiting immunopathological exacerbation. The use of this antibody could provide an important therapy for treatment of COVID-19 patients.

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